Hi, I'd really like to play this, but I've never modded Serious Sam before. I have placed the contents of all four chapter files into the root directory, and the contents of TheSequel.rar into the mod folder. Currently, it crashes upon starting a new game and skipping the intro video. "Cannot open the file \Serious Sam Classic the Second Encounter\ModelsF\Weapons\Crossbow\Crossbowitem.mdl (no such file or directory).
Viewing post in Serious Sam: The Sequel (Public Beta) comments
I think last update kinda broke some things. Forgot that each gun's model is loaded on each level start and not just the levels that have them as pickups, so now it might be looking for models that aren't there anymore. You can just put the new models in their old places and rename things. I might release a small update to fix this issue.
By the way, you don't put anything into the root directory. Everything goes into the mod's folder.